As disclosed in, for example, Patent Literature 1, there is known a compressor that supercharges a compression subject fluid upon injection of the compression subject fluid into the compressor. Known electric compressors for refrigerating and air conditioning include an electric compressor having a compressing unit of a reciprocating type, an electric compressor having a compressing unit of a rotary type, and an electric compressor having a compressing unit of a scroll type. Among these types, the compressor of the scroll type has been practically used by utilizing the characteristics of the high efficiency, the low noise level and the low vibration level. In the compressor of the scroll type, a refrigerant gas of an intermediate pressure is injected through a check valve into a compression chamber formed between a stationary scroll and an orbiting scroll to implement the stable and efficient gas injection by utilizing the moderate compression that is the characteristic of the compressor of the scroll type. However, in a case where a path, which extends from the check valve to the compression chamber formed between the stationary scroll and the orbiting scroll, is complicated and is long, it is known that a dead volume becomes large to cause adverse influence on the compression efficiency, an increase in the amount of intrusion of a lubricating oil, unstableness of the lubrication caused by deterioration of draining, and unstableness of the performance.
In the prior art technique of Patent Literature 1, an injection port is formed in an end plate of the stationary scroll in such a manner that the injection port penetrates through the end plate from a back surface side of the end plate to the compression chamber in a wall thickness direction of the end plate. A block, to which an injection pipe is connected, is engaged with an outer surface of the end plate of the stationary scroll, which corresponds to the injection port, and a check valve chamber is formed between the end plate and the block. A reed valve element is fixed with bolts to a guide inlet of the block, which is connected with the injection pipe, to form a check valve. In this instance, the guide inlet of the injection pipe and the injection port are coaxially arranged. Furthermore, a valve stopper of the reed valve element is formed in a portion of the check valve chamber.
The prior art technique of Patent Literature 1 is the one that has a simple structure and a relatively small dead volume and can limit re-expansion of a compressible fluid and outflow of a lubricant oil. However, the following disadvantages (1)-(3) have been encountered.
(1) In the prior art technique, attention is not given to a relationship between a lifting direction of the reed valve element and a location of the injection port, so that depending on the positional relationship discussed above, a flow passage resistance may possibly become high, and an injection flow quantity may possibly be reduced. Furthermore, a size of the reed valve element is large. Therefore, when it is desirable to further reduce the dead volume, there will be a mounting difficulty.
(2) In the prior art technique, the bolts, which fix the reed valve element, are required. Therefore, the component costs are increased. Furthermore, the number of assembling steps is increased, and thereby the assembling costs are increased.
(3) Normally, in the case where the reed valve element is used, the valve stopper is required. In the prior art technique, there is the disclosure about the formation of the valve stopper, and the formation of the valve stopper requires a separate processing step, which is separate from a processing step of the refrigerant passage.
Besides the above prior art technique, Patent Literature 2 discloses a compressor of a refrigeration cycle, into which an intermediate pressure gas is injected. In Patent Literature 2, a reed valve element, which opens or closes in a direction perpendicular to an axial direction of an injection port that projects from a back surface of a stationary scroll, is inserted into the injection port, so that a dead volume cannot be reduced, and there is a disadvantage with respect to provision of an axial space. Patent Literature 3 recites a compressor, in which liquid injection is executed, and a plug is fitted into a connecting conduit, which is communicated with an injection port, to limit gasification of the liquid. In this compressor, a dead volume cannot be reduced when the dead volume of the entire flow passage is considered.